Revert "Debug info: Let dbg.values inserted by LowerDbgDeclare inherit the location"

This reverts commit 207130 for buildbot breakage.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@207159 91177308-0d34-0410-b5e6-96231b3b80d8
Revert "Debug info for optimized code: Support variables that are on the stack and"

This reverts commit 207130 for buildbot breakage.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@207162 91177308-0d34-0410-b5e6-96231b3b80d8
This reapplies r207130 with an additional testcase+and a missing check for
AllocaInst that was missing in one location.
Debug info for optimized code: Support variables that are on the stack and
described by DBG_VALUEs during their lifetime.

Previously, when a variable was at a FrameIndex for any part of its
lifetime, this would shadow all other DBG_VALUEs and only a single
fbreg location would be emitted, which in fact is only valid for a small
range and not the entire lexical scope of the variable. The included
dbg-value-const-byref testcase demonstrates this.

This patch fixes this by
Local
- emitting dbg.value intrinsics for allocas that are passed by reference
- dropping all dbg.declares (they are now fully lowered to dbg.values)
SelectionDAG
- renamed constructors for SDDbgValue for better readability.
- fix UserValue::match() to handle indirect values correctly
- not inserting an MMI table entries for dbg.values that describe allocas.
- lowering dbg.values that describe allocas into *indirect* DBG_VALUEs.
CodeGenPrepare
- leaving dbg.values for an alloca were they are (see comment)
Other
- regenerated/updated instcombine.ll testcase and included source

rdar://problem/16679879
http://reviews.llvm.org/D3374

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@207165 91177308-0d34-0410-b5e6-96231b3b80d8
Revert "This reapplies r207130 with an additional testcase+and a missing check for"
Typo in testcase.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@207166 91177308-0d34-0410-b5e6-96231b3b80d8
Fix quadratic performance during debug compression due to sections x symbols iteration.

When fixing the symbols in each compressed section we were iterating
over all symbols for each compressed section. In extreme cases this
could snowball severely (5min uncompressed -> 35min compressed) due to
iterating over all symbols for each compressed section (large numbers of
compressed sections can be generated by DWARF type units).

To address this, build a map of the symbols in each section ahead of
time, and access that map if a section is being compressed. This brings
compile time for the aforementioned example down to ~6 minutes.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@207167 91177308-0d34-0410-b5e6-96231b3b80d8